CN114790937B - Control device for internal combustion engine - Google Patents

Abstract

A control device for an internal combustion engine is provided, which is applied to an internal combustion engine including a variable-section turbocharger having a turbine with a variable nozzle and an actuator that controls the opening degree of the variable nozzle, and a throttle valve disposed in an intake passage. The control device is provided with an electronic control unit. The electronic control unit includes a first control mode that is one of the control modes of the intake air amount. In the first control mode, when the air quantity region on the high flow rate side including the maximum value of the required air quantity of the internal combustion engine is referred to as a high air quantity region, the electronic control unit is configured to control the actuator and the throttle valve so that the throttle valve opening is increased while maintaining the fully-closed opening of the variable nozzle with respect to the increase of the required air quantity on the maximum value side of the high air quantity region.

Description

Control devices for internal combustion engines

technical field

The present invention relates to a control device for an internal combustion engine equipped with a variable geometry turbocharger.

Background technique

JP 2011-085048 discloses a control device for an internal combustion engine including a variable geometry turbocharger. It discloses a technique in which the control device rapidly reduces the turbine speed by closing a variable nozzle (nozzle vane) in order to suppress the conspicuousness of the noise generated by the rotation of the turbocharger when the engine speed drops rapidly.

Contents of the invention

In the high-load region of the internal combustion engine (especially on the low-speed side), the main cause of exhaust noise is the explosive first-order component of combustion, and the greater the amplitude value of the exhaust pressure pulsation accompanying the explosion, the greater the exhaust noise becomes. big. The technique described in Japanese Patent Laid-Open No. 2011-085048 cannot be applied to suppress exhaust noise in such a high-load region (high air volume region).

The present invention has been made in view of the above-mentioned problems, and provides a control device for an internal combustion engine capable of utilizing control including variable nozzle opening in an internal combustion engine equipped with a variable area turbocharger. The intake air volume control suppresses the exhaust noise in the high-load area and enables the required engine torque to be achieved.

A first aspect of the present invention relates to a control device applied to an internal combustion engine, the internal combustion engine comprising a variable-section turbocharger and a throttle valve arranged in an intake passage, the variable-section turbocharger having a The turbine of the variable nozzle and the actuator configured to control the opening of the variable nozzle. This control device includes an electronic control unit configured as follows. That is, the electronic control unit includes the first control mode as one of the control modes of the intake air amount. Furthermore, the electronic control unit is configured such that, when an air volume region on a high flow side including a maximum required air volume of the internal combustion engine is referred to as a high air volume region, in the first control mode, the high On the maximum value side in the air volume range, the actuator is controlled so that the throttle valve opening is increased while maintaining the variable nozzle at a fully closed opening or a substantially fully closed opening in response to an increase in the required air volume. and the throttle valve, or, on the maximum value side in the high air volume region, the actuator is controlled to increase the throttle valve opening while decreasing the variable nozzle opening in response to an increase in the required air volume. and throttle.

In the above-mentioned control device of the first aspect, the electronic control unit may include a second control mode as another control mode among the control modes. Furthermore, the electronic control unit may be configured such that, in the second control mode, on the maximum value side in the high air volume region, the throttle valve is kept fully open with respect to an increase in the required air volume. The actuator and the throttle valve are controlled in such a manner that the opening of the variable nozzle is decreased while substantially opening the opening.

The second aspect of the present invention relates to a control device applied to an internal combustion engine, which includes a variable-section turbocharger, a throttle valve disposed in an intake passage, and a variable valve mechanism, and the variable-section turbocharger The compressor has a turbine with a variable nozzle and an actuator configured to control the opening of the variable nozzle, and the variable valve mechanism is configured to change the opening characteristic of the intake valve. The control device includes an electronic control unit configured as follows. That is, the electronic control unit includes the first control mode as one of the control modes of the intake air amount. In addition, the electronic control unit is configured such that, when an air volume region on a high flow side including a maximum required air volume of the internal combustion engine is referred to as a high air volume range, in the first control mode, the high air volume On the maximum value side in the range, the actuator is controlled in such a way that the variable nozzle maintains a fully closed opening degree or a substantially fully closed opening degree, or the variable nozzle opening degree decreases in response to an increase in the required air volume, While controlling the throttle valve and variable valve mechanism to meet the required air volume.

In the control device of the second aspect described above, the electronic control unit may include a second control mode as another control mode among the control modes. Furthermore, the electronic control unit may be configured such that, in the second control mode, on the maximum value side in the high air volume region, the throttle valve is kept fully open with respect to an increase in the required air volume. The actuator and the throttle valve are controlled in such a manner that the opening of the variable nozzle is decreased while substantially opening the opening.

In the composition of the control device of the above-mentioned first solution and the second solution, it may be that the electronic control unit is configured such that, in the first control mode, with respect to the increase of the required air volume, in accordance with the second control mode The actuator is controlled in such a way that the variable nozzle starts to close from a fully open opening at a specific required air volume value less than that during the execution of the valve.

In the configuration of the control device of the above-mentioned first aspect and the second aspect, the electronic control unit may be configured such that, in the first control mode, the air volume on the high flow side is higher than the specific required air volume value. In the region, the actuation is controlled in such a way that the variable nozzle maintains the fully closed opening degree or the substantially fully closed opening degree after gradually decreasing the variable nozzle opening degree toward the fully closed opening degree with respect to the increase in the required air volume. device.

In the above-mentioned control devices of the first aspect and the second aspect, the internal combustion engine may include an ignition device. In addition, the electronic control unit may be configured so that when the first control mode is selected under the engine operating condition that the basic ignition timing on the retard side relative to the optimal ignition timing is selected, in order to approach the optimal ignition timing The ignition timing is controlled in such a way that the ignition timing is advanced from the base ignition timing. In addition, the electronic control unit may be configured to correct the variable nozzle opening degree set in the first control mode to the closed side by an amount that cancels the fuel economy associated with the advancement of the ignition timing. Improve the amount of the amount.

In the control devices of the first and second aspects described above, the vehicle equipped with the internal combustion engine may include an input device configured to receive a noise priority request to prioritize exhaust noise reduction over fuel economy from the driver. Furthermore, the electronic control unit may be configured to select the first control mode when the input device accepts a noise priority request.

In the above-mentioned control devices according to the first aspect and the second aspect, the electronic control unit may be configured so that when a vehicle equipped with an internal combustion engine is in a place and a time period where the reduction of exhaust noise should be prioritized over fuel economy, In the case of traveling in at least one of them, the first control mode is selected.

In the above-mentioned control devices of the first aspect and the second aspect, the vehicle equipped with the internal combustion engine may include a noise meter configured to measure exhaust noise emitted from the exhaust port. Furthermore, the electronic control unit may be configured to select the first control mode when the value of the exhaust noise measured by the noise meter is higher than a threshold value.

According to the control device according to the first aspect of the present invention, in the first control mode, on the maximum value side in the high air volume region, the variable nozzle is kept fully closed with respect to an increase in the required air volume. or substantially fully closed opening, the actuator and the throttle valve are controlled by increasing the throttle opening, or the actuator is controlled by increasing the throttle opening while decreasing the variable nozzle opening. and throttle. In this way, when the first control mode is selected, on the maximum value side in the high air volume region, the intake air is controlled by the throttle valve so that the required air volume is satisfied while the exhaust passage is throttled by the variable nozzle. air volume. Therefore, according to the first aspect, it is possible to suppress the exhaust noise in the high load region and realize the required engine torque by the intake air amount control including the control of the variable nozzle opening degree.

In addition, according to the control device according to the second aspect of the present invention, in the first control mode, the variable nozzle is kept fully closed with respect to an increase in the required air volume on the maximum value side in the high air volume range. The throttle valve and the variable valve mechanism are controlled so as to satisfy the required air volume while controlling the actuator so as to reduce the opening degree, the substantially fully closed opening degree, or the variable nozzle opening degree. In this way, when the first control mode is selected, on the maximum value side in the high air volume region, the throttle valve and the variable nozzle are used to satisfy the required air volume under the condition that the exhaust passage is throttled by the variable nozzle. The valve train controls the intake air volume. Therefore, according to this second aspect as well, it is possible to suppress the exhaust noise in the high load region and realize the required engine torque by the intake air amount control including the control of the variable nozzle opening degree.

Description of drawings

The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

FIG. 1 is a schematic diagram showing an example of a system configuration of an internal combustion engine according to a first embodiment of the present invention.

2 is a graph for explaining a fuel economy priority mode and a noise priority mode in the first embodiment.

3 is a graph showing an example of the relationship between exhaust pressure pulsation and crank angle in the first embodiment.

FIG. 4 is a graph showing an example of the relationship between each sound pressure level of BSFC (Effective Fuel Consumption) and exhaust noise and the VN opening degree in the first embodiment.

5 is a graph for explaining the influence of a change in the VN opening degree to the closed side with respect to each sound pressure level of BSFC and exhaust noise in the first embodiment.

FIG. 6 is a flowchart showing processing related to intake air amount control in the first embodiment.

FIG. 7A is a graph for the fuel economy priority mode, and is a graph showing the relationship of the VN opening degree with respect to the required air amount and the engine speed.

FIG. 7B is a graph for the fuel economy priority mode, and is a graph showing the relationship between the throttle opening degree, the required air amount, and the engine speed.

FIG. 8A is a graph for the noise priority mode, and is a graph showing the relationship of the VN opening degree with respect to the required air amount and the engine speed.

FIG. 8B is a graph for the noise priority mode, and is a graph showing the relationship between the throttle opening degree, the required air amount, and the engine speed.

9 is a graph for explaining another setting example of the VN opening used in the noise priority mode of the first embodiment.

10 is a graph for explaining a fuel economy priority mode and a noise priority mode according to the second embodiment of the present invention.

11 is a schematic diagram showing an example of a system configuration of an internal combustion engine according to a third embodiment of the present invention.

12 is a graph for explaining a fuel economy priority mode and a noise priority mode in the third embodiment.

13 is a flowchart showing calculation processing of the VN opening in the noise priority mode using the VN opening correction method according to the fourth embodiment of the present invention.

FIG. 14 is a graph showing the relationship between BSFC and ignition timing in the fourth embodiment.

FIG. 15 is a graph showing the relationship between the BSFC and the VN opening used in step S208 shown in the flowchart of FIG. 13 .

Detailed ways

In each of the embodiments described below, the same reference numerals are assigned to the same components in the drawings, and overlapping descriptions are omitted or simplified. In addition, when numerical values such as the number, amount, amount, and range of each element are mentioned in the embodiments described below, the present invention shall not be limited to those numerical values, except in the cases where it is specifically stated or clearly defined as such numerical values in principle. Not limited to the mentioned number. In addition, the structures, procedures, and the like described in the embodiments described below are not necessarily essential to the present invention, except for cases where it is particularly clearly stated or clearly defined as the above-mentioned structures, steps, and the like in principle.

A first embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing an example of a system configuration of an internal combustion engine 10 according to a first embodiment. An internal combustion engine 10 shown in FIG. 1 includes a turbocharger 12 of variable cross-section type. The turbocharger 12 includes a compressor 16 arranged in the intake passage 14 and a turbine 20 arranged in the exhaust passage 18 . The turbine 20 has a variable nozzle 22 . The turbine 20 is rotated by exhaust gas flowing in the exhaust passage 18 . The compressor 16 is rotated by the turbine 20 and compresses intake air.

The turbocharger 12 further includes a VN actuator 24 that controls the opening degree (VN opening degree α) of the variable nozzle (VN) 22 . The VN actuator 24 is, for example, a diaphragm type or an electric type. When the VN opening degree α becomes smaller (controlled toward the closed side), the inlet area of the turbine 20 becomes smaller, and the flow velocity of the exhaust gas flowing into the turbine 20 becomes higher. The VN actuator 24 can adjust the amount of exhaust energy recovered by the turbine 20 by adjusting the VN opening degree α to vary the flow velocity of the exhaust gas flowing into the turbine 20 . The VN actuator 24 controls the VN opening degree α within a predetermined opening degree control range from a fully closed opening (minimum opening) to a fully open opening (maximum opening). That is, the fully closed opening degree and the fully open opening degree are opening degrees in a state where the VN22 is operated so as to obtain the minimum flow path area and the maximum flow path area, respectively.

An intercooler 26 that cools intake air compressed by the compressor 16 is disposed downstream of the compressor 16 in the intake passage 14 . An electronically controlled throttle valve 28 is disposed downstream of the intercooler 26 . The amount of intake air is controlled by adjusting the opening of the throttle valve 28 .

One or more exhaust purification catalysts (typically three-way catalysts) 30 are arranged downstream of the turbine 20 in the exhaust passage 18 . A muffler 32 is disposed downstream of the exhaust purification catalyst 30 . A vehicle equipped with the internal combustion engine 10 includes a noise meter 36 that measures exhaust noise emitted from an exhaust port 34 corresponding to the outlet of the muffler 32 (the outlet of the exhaust passage 18 ).

The system shown in FIG. 1 further includes an electronic control unit (ECU) 40 as a control device for controlling the internal combustion engine 10 . The ECU 40 has a processor 40a and a memory 40b. Various data including maps used for various controls of the internal combustion engine 10 and various control programs are stored in the memory 40b. The processor 40a realizes various processes and controls of the ECU 40 by reading and executing a control program from the memory 40b. In addition, there may be a plurality of ECU40.

The ECU 40 acquires sensor signals from sensors 42 used for various controls of the internal combustion engine 10 . The sensors 42 mentioned here include various sensors mounted on the internal combustion engine 10 (such as a crank angle sensor, an engine water temperature sensor, an intake air temperature sensor, and an air flow sensor) and various sensors mounted on a vehicle (such as an accelerator position sensor). ). In addition, the actuators controlled by the ECU 40 include a fuel injection device 44 and an ignition device 46 of the internal combustion engine 10 in addition to the VN actuator 24 and the throttle valve 28 described above.

In addition, an input device 48 and a GNSS (Global Navigation Satellite System: Global Navigation Satellite System) receiver 50 are mounted on a vehicle equipped with the internal combustion engine 10 . The input device 48 is an HMI (Human Machine Interface: Human Machine Interface) device such as a button or a touch panel. The ECU 40 can receive a “noise priority request” or a “fuel economy priority request” described later through the input device 48 . Furthermore, ECU 40 can acquire positional information (travel location information) of the vehicle using GNSS receiver 50 .

Next, the intake air amount (engine torque) control in consideration of exhaust noise suppression will be described. The control mode based on the intake air amount (g/s) of the ECU 40 includes a "fuel economy priority mode" and a "noise priority mode" which prioritizes fuel economy over exhaust noise reduction A basic (in other words, usual) mode, the "noise priority mode" is a mode that prioritizes exhaust noise reduction over fuel economy. In addition, the fuel economy priority mode and the noise priority mode correspond to examples of the "second control mode" and the "first control mode" in the present invention, respectively. In addition, the intake air amount control mode may include not only these two control modes, but also any one or more control modes for other purposes (for example, a control mode that prioritizes engine output).

2 is a graph for explaining a fuel economy priority mode and a noise priority mode in the first embodiment. In each of the above control modes, the intake air amount is controlled so as to satisfy the required air amount Ga by using the control of the VN opening α by the VN actuator 24 and the control of the throttle valve opening θ by the throttle valve 28 . In FIG. 2 , settings of the throttle opening θ and the VN opening α are shown with respect to the required air amount Ga on the horizontal axis. The waveforms of the throttle valve opening θ and the VN opening α shown in FIG. 2 show the relationship at a constant engine speed.

Furthermore, as shown in FIG. 2 , the engine torque becomes higher basically in proportion to the increase in the required air amount Ga (in other words, the engine load becomes higher). Therefore, even when the horizontal axis is replaced by the engine torque, the settings of the throttle opening θ and the VN opening α can be obtained similarly to the configuration shown in FIG. 2 . This point is also the same for the settings shown in FIGS. 10 and 12 described later.

Next, the fuel economy priority mode will be described. As shown by the solid line in FIG. 2 , on the low air amount side in the fuel economy priority mode, the throttle opening θ is increased while maintaining the full opening of VN22 in response to an increase in the required air amount Ga. On the other hand, on the high air volume side including the high air volume region R1 described later, the VN opening degree α is decreased while maintaining the throttle valve 28 fully open in response to an increase in the required air volume Ga. The maximum value Gamax of the requested air amount Ga is obtained when the throttle valve opening θ is fully open and the VN opening α is fully closed. In addition, in the air volume region in which the throttle valve 28 maintains the full opening degree in FIG. 2 , it may be set so that the throttle valve opening degree θ is slightly increased with respect to the increase in the required air volume Ga, unlike the example shown in FIG. 2 . The slope of increases, and reaches the full opening degree at the maximum value Gamax (ie, in this air volume region, the throttle valve 28 can also maintain a substantially full opening degree).

In the example shown in FIG. 2 , VN 22 starts to close from the fully open position when the throttle valve opening θ is close to the fully open position with respect to the increase in the required air volume Ga. Instead of such an example, VN22 may be started to close in coincidence with "throttle valve opening degree θ reaching full opening degree".

According to the fuel economy priority mode described above, on the low air amount side, the intake air amount is controlled by adjusting the throttle opening θ with the VN22 set to the fully closed opening. Further, on the high air volume side, the intake air volume is controlled by adjusting the VN opening degree α with the throttle valve 28 fully opened. In this way, according to the fuel economy priority mode, since the throttle valve opening θ is as large as possible in each air volume region, it is possible to control the intake air volume while reducing the pump loss (that is, improving fuel economy).

Next, the noise priority mode will be described. Before specifically describing the noise priority mode, the exhaust noise to be reduced in the first embodiment and the relationship between the exhaust noise and the VN opening degree α will be described.

In the high load range (more specifically, the middle load to high load range), the main cause of the exhaust noise is the explosive first-order component of combustion especially on the low rotation speed side. And, the larger the amplitude value of the exhaust pressure pulsation accompanying the explosion, the larger the exhaust noise becomes. 3 is a graph showing an example of the relationship between exhaust pressure pulsation and crank angle. FIG. 3 shows the waveform of the exhaust pressure pulsation (before the turbine) at the upstream side of the turbine 20 and the waveform of the exhaust pressure pulsation (after the turbine) at the downstream side of the turbine 20 . When the turbocharger 12 is provided, part of the exhaust energy is recovered by the turbine 20 . Therefore, the more work done by the turbine 20, the less energy of the exhaust gas passing through the turbine. And, accompanying this decrease in exhaust energy, as shown in FIG. 3 , the amplitude of the exhaust pressure pulsation after the turbine is smaller than the amplitude of the exhaust pressure pulsation before the turbine. As a result, exhaust noise emitted from the exhaust port 34 is reduced.

4 is a graph showing an example of the relationship between the BSFC (effective fuel consumption rate) and the sound pressure level of the exhaust noise and the VN opening degree α. FIG. 4 shows the relationship between the required air amount Ga and the engine speed at a constant value. In FIG. 4 , as an example, it is shown that the opening control range by the VN actuator 24 is divided into three equal parts: a large opening area (including a full opening opening), a middle opening area, and a small opening area. (including the fully closed opening) and the relationship between the VN opening α shown. In each opening area, the VN opening α becomes smaller as it goes to the right side of the drawing.

In the internal combustion engine 10 provided with the variable-section turbocharger 12, by controlling the VN opening α to the closed side, the recovery amount of exhaust energy in the turbine 20 can be effectively increased. As a result, as shown in FIG. 4 , Can reduce exhaust noise. On the other hand, by controlling the VN opening α to the closed side, the pump loss increases. Therefore, basically, when the VN22 is turned off, the BSFC (fuel economy) deteriorates.

Therefore, in the noise priority mode, the recovery amount of exhaust energy in the turbine 20 is increased by controlling the VN22 to the closed side within the allowable fuel economy deterioration range in order to prioritize exhaust noise reduction over fuel economy.

Specifically, as shown by the dotted line in FIG. 2 , in the noise priority mode, VN22 starts at a specific required air amount Ga1 that is less than during execution of the fuel economy priority mode with respect to an increase in the required air amount Ga. Closes from full opening. On the low flow side of the specific required air volume value Ga1 or less, the settings of the VN opening degree α and the throttle valve opening degree θ in the noise priority mode are the same as those in the fuel economy priority mode.

On the other hand, on the high flow side higher than the specific required air quantity value Ga1, the throttle valve opening θ is increased in order to satisfy the required air quantity Ga while the VN opening α decreases with respect to the increase of the required air quantity Ga. More specifically, in the example shown in FIG. 2 , the VN opening degree α is gradually (monotonically) decreased toward the fully closed opening degree and then maintained at the fully closed opening degree with respect to an increase in the required air amount Ga. Also, the air volume region in which the VN22 and the throttle valve 28 are controlled in this way includes the high air volume area R1. As shown in FIG. 2 , this high air volume region R1 is included in the high air volume region on the high flow rate side including the maximum value Gamax, and more specifically, it is the air volume region on the maximum value Gamax side among such high air volume regions. . In the high air volume region R1 , the throttle opening θ is increased while maintaining the fully closed opening of the VN 22 in response to an increase in the required air volume Ga. More specifically, in the example shown in FIG. 2 , the throttle valve opening θ gradually (monotonically) increases with an increase in the required air amount Ga.

In addition, FIG. 2 also shows the relationship between BSFC (fuel economy) and the required air amount Ga. Comparing the waveforms of the solid line and the dotted line in Figure 2, it can be seen that in the air volume area on the high flow side of the specific required air volume value Ga1 in the noise priority mode, it is different from the air volume area in the fuel economy priority mode. In contrast, both the VN opening degree α and the throttle valve opening degree θ are controlled toward the closing side. Therefore, in the noise priority mode, the BSFC (fuel economy) is deteriorated compared with the fuel economy priority mode, while exhaust noise can be reduced for the above-mentioned reason.

FIG. 5 is a graph for explaining the influence of "the change of the VN opening degree α to the closed side" on the sound pressure levels of BSFC and exhaust noise, respectively. FIG. 5 shows the relationship between the required air amount Ga and the engine speed at a constant value. In FIG. 5 , three values α1 to α3 of the VN opening are shown (α1>α2>α3). In the example shown in FIG. 5 , when the VN22 is closed from the VN opening value α1 to the VN opening value α2, the BSFC becomes the same magnitude, but the exhaust noise is reduced by 1 dB. Also, when VN22 is closed from the VN opening value α1 to the VN opening value α3, the BSFC deteriorates by 2.2%, but the exhaust noise decreases by 5dB.

As illustrated in FIG. 5 , BSFC (fuel economy) and exhaust noise are in a trade-off relationship with respect to a change in the VN opening degree α toward the closed side. That is, the "reduction amount of exhaust noise by controlling the VN opening degree α toward the closed side" differs depending on "to what extent deterioration in fuel economy is tolerable". In other words, "to what extent the VN opening degree α can be controlled to the closed side to reduce exhaust noise" differs depending on "how much fuel economy can be tolerated". Therefore, as an example, the VN opening degree α at each required air amount Ga in the noise priority mode indicated by a dotted line in FIG. The manner in which the amount of economical deterioration becomes a value on the closed side with respect to the VN opening degree α in the fuel economy priority mode within the allowable range is determined in advance.

Next, processing by the ECU will be described. FIG. 6 is a flowchart showing processing related to intake air amount control in the first embodiment. The processing of this flowchart is repeatedly executed during operation of the internal combustion engine 10 .

In FIG. 6 , the ECU 40 first calculates the required air amount Ga in step S100 . Specifically, the ECU 40 calculates, for example, an air amount required to realize the required engine torque corresponding to the accelerator opening detected by the accelerator position sensor as the required air amount Ga. Then, the process proceeds to step S102.

In step S102, the ECU 40 determines whether or not the reduction of exhaust noise is prioritized over fuel economy. This determination can be performed by, for example, the following first to third methods.

First, in the first method, the input device 48 is used. The driver of the vehicle can alternatively input a noise priority request to prioritize exhaust noise reduction over fuel economy and a fuel economy priority request to prioritize fuel economy over exhaust noise reduction using the input device 48 . When the input device 48 accepts the noise priority request, the ECU 40 determines that the exhaust noise reduction is prioritized (step S102: Yes), and on the other hand, when the input device 48 accepts the fuel economy priority request, It is determined that the fuel economy is prioritized (step S102: NO). That is, according to the first method, the driver selects the control mode of the intake air amount.

Next, in the second method, the current position information (current traveling location) of the vehicle acquired by the GNSS receiver 50 is used. For example, when the vehicle is traveling in an urban area or a residential area, the ECU 40 determines that the vehicle is traveling in a place where exhaust noise reduction should be prioritized over fuel economy (that is, it is determined that the exhaust noise reduction is prioritized). (Step S102: Yes). On the other hand, for example, when the vehicle is traveling in the suburbs, the ECU 40 determines that the vehicle is traveling in a place where fuel economy should be prioritized over exhaust noise reduction (that is, it is determined that fuel economy is prioritized) ( Step S102: No).

In addition, in the second method, the current time zone acquired by the timekeeping function of the ECU 40 is used. For example, when the current time zone is late at night or early in the morning, the ECU 40 determines that the vehicle is running during a time zone in which exhaust noise reduction should be prioritized over fuel economy (that is, it is determined that exhaust noise reduction is prioritized) (step S102: Yes). On the other hand, for example, when the current time zone is daytime, the ECU 40 determines that the vehicle is traveling in a time zone in which fuel economy should be prioritized over exhaust noise reduction (that is, it is determined that fuel economy is prioritized). (Step S102: No). In addition, in the second method, instead of the above example, only one of the traveling location and the time zone may be used.

Next, in the third method, the ECU 40 uses the noise meter 36 . When the exhaust noise value (typically sound pressure level) measured by the noise meter 36 is higher than a predetermined threshold value, the ECU 40 determines that it is a situation that gives priority to exhaust noise reduction (step S102: Yes), and another On the other hand, when the value of the measured exhaust noise is equal to or less than the threshold value, it is determined that the fuel economy is prioritized (step S102: NO).

If the exhaust noise reduction is not a priority in step S102, the ECU 40 selects the fuel economy priority mode, and the process proceeds to step S104. In step S104, the VN opening degree α is calculated according to the fuel economy priority mode. Specifically, in the memory 40b of the ECU 40, as shown in FIG. 7A below, a map for determining the VN opening degree α based on the relationship between the required air amount Ga and the engine speed is stored. The ECU 40 calculates the VN opening degree α (target VN opening degree) corresponding to the current required air amount Ga and the engine speed based on such a map.

7A is a graph showing the relationship of the VN opening degree α with respect to the required air amount Ga and the engine speed used in the fuel economy priority mode. In FIG. 7A, it is shown that the opening control range based on the VN actuator 24 is divided into three equal parts: a large opening area (including a full opening), a middle opening area, and a small opening area (including a full opening). Closed opening) and the relationship between the VN opening α shown. Here, when the relationship shown in FIG. 7A is observed at the same engine speed, the setting of the VN opening degree α as shown by the solid line in FIG. 2 can be obtained at each engine speed. In addition, according to the setting shown in FIG. 7A , as shown in the boundary line between two adjacent opening regions in FIG. 7A , when the VN opening degree α is constant, the higher the engine speed, the higher the value of the required air amount Ga becomes. get higher.

On the other hand, in step S102, when the exhaust noise reduction is prioritized, the ECU 40 selects the noise priority mode, and the process proceeds to step S106. In step S106, the VN opening degree α is calculated according to the noise priority mode. Specifically, as shown in the following FIG. 8A , a map for determining the VN opening degree α from the relationship with the required air amount Ga and the engine speed is stored in the memory 40 b. The ECU 40 calculates the VN opening degree α (target VN opening degree) corresponding to the current required air amount Ga and the engine speed based on such a map.

FIG. 8A is a graph showing the relationship of the VN opening degree α with respect to the required air amount Ga and the engine speed used in the noise priority mode. Here, differences between the settings shown in FIG. 8A and the settings shown in FIG. 7A will be described. As already explained, the VN opening degree α (refer to the dotted line in FIG. 2 ) at each required air amount Ga used in the noise priority mode is determined in consideration of the allowable deterioration of fuel economy. The high flow rate side of the requested air quantity value Ga1 is a value on the close side with respect to the VN opening degree α (see the solid line in FIG. 2 ) used in the fuel economy priority mode. Based on the difference in the waveforms of the VN opening α between the solid line and the dotted line in FIG. 2 , the middle opening region in FIG. 8A is shifted to the lower air volume side than the middle opening region shown in FIG. 7A . As a result, the large opening area in FIG. 8A is narrowed toward the low air volume side compared to the large opening area in FIG. 7A . In addition, the small opening degree region in FIG. 8A is enlarged toward the lower air volume side than the small opening degree region in FIG. 7A .

In step S108 subsequent to step S104 or S106, the ECU 40 calculates the throttle opening θ. Specifically, when proceeding to step S108 after step S104 , the ECU 40 calculates the throttle opening θ according to the fuel economy priority mode. Specifically, as shown in the next FIG. 7B , the memory 40 b stores a map for determining the throttle valve opening degree θ based on the relationship between the required air amount Ga and the engine speed. Based on such a map, the ECU 40 calculates the throttle opening θ (target throttle opening) corresponding to the current required air amount Ga and the engine speed.

FIG. 7B is a graph showing the relationship of the throttle opening θ with respect to the required air amount Ga and the engine speed used in the fuel economy priority mode. In FIG. 7B , it is shown that the opening control range based on the throttle valve 28 is divided into three equal parts: a large opening area (including a fully open opening), a middle opening area, and a small opening area (including a fully closed opening). degrees) and the relationship between the throttle opening θ shown. Here, when the relationship shown in FIG. 7B is observed at the same engine speed, the setting of the throttle opening θ as shown by the solid line in FIG. 2 can be obtained at each engine speed. According to the setting shown in FIG. 7B, as shown in the boundary line of two adjacent opening regions in FIG. 7B, when the throttle valve opening θ is constant, the higher the engine speed, the value of the required air amount Ga becomes higher.

In addition, in step S108, when the ECU 40 proceeds to step S108 after step S106, it calculates the throttle opening θ according to the noise priority mode. Specifically, as shown in the next FIG. 8B , a map for determining the throttle opening θ based on the relationship between the required air amount Ga and the engine speed is stored in the memory 40 b. Based on such a map, the ECU 40 calculates the throttle opening θ (target throttle opening) corresponding to the current required air amount Ga and the engine speed.

FIG. 8B is a graph showing the relationship of the throttle opening θ with respect to the required air amount Ga and the engine speed used in the noise priority mode. Here, differences between the settings shown in FIG. 8B and the settings shown in FIG. 7B will be described. Based on the difference in the waveforms of the throttle valve opening θ between the solid line and the dotted line in FIG. 2 described above, the middle opening region in FIG. 8B is enlarged toward the high air volume side compared to the middle opening region shown in FIG. 7B . As a result, the large opening area in FIG. 8B is narrowed toward the high air volume side compared to the large opening area in FIG. 7B . On the other hand, the small opening area in FIG. 8B is the same as the small opening area in FIG. 7B.

According to the processing of step S108 described above, the throttle valve opening θ required to satisfy the required air amount Ga is calculated at the VN opening α calculated in step S104 or S106 .

Furthermore, the ECU 40 controls the VN actuator 24 and the throttle valve 28 so that the VN opening α and the throttle opening θ calculated by the processing of the flowchart shown in FIG. 6 are realized.

Next, effects will be described. According to the noise priority mode of the first embodiment described above, in the high air volume region R1 including the maximum value Gamax of the required air volume Ga, VN22 is kept fully closed while maintaining the full-closed opening degree in response to an increase in the required air volume Ga. The valve opening θ increases. That is, in the high air volume region R1 (high load region), the exhaust passage 18 is reduced by the VN22 (more specifically, the exhaust passage 18 is reduced compared to the fuel economy priority mode). In order to satisfy the required air amount Ga, the throttle valve 28 is used to control the intake air amount. Therefore, the required engine torque can be realized while reducing the exhaust noise.

As described above, according to the first embodiment, it is possible to suppress the exhaust noise in the high load region and realize the required engine torque by the intake air amount control including the control of the VN opening degree α. In addition, the exhaust noise caused by the explosive first-order components of the combustion described above is low frequency. When it is desired to reduce such exhaust noise with the muffler 32 , the volume of the muffler 32 becomes large, or the pressure loss of the exhaust passage 18 becomes large. On the other hand, according to the first embodiment, the above-mentioned exhaust noise can be reduced by the control of the intake air amount including the control of the VN opening degree α. It is preferable from the viewpoint of pressure loss reduction.

In addition, in the intake air amount control of the first embodiment, a fuel economy priority mode can be selected in addition to the noise priority mode. According to the fuel economy priority mode, in the high air volume region R1 , the VN opening degree α is decreased while maintaining the throttle valve 28 fully open in response to an increase in the required air volume Ga. Therefore, not only can the exhaust noise be suppressed by selecting the noise priority mode as described above, but also by selecting the fuel economy priority mode, the exhaust passage resistance in the high-load region is small (that is, the pump loss is suppressed less). low state) to achieve the required engine torque while achieving low fuel consumption.

Furthermore, according to the first embodiment, by using the input device 48 , switching between the noise priority mode and the fuel economy priority mode as described above can be performed according to the driver's request of the vehicle. In addition, according to the first embodiment, it is possible to automatically switch the mode from the noise priority mode and the fuel economy priority mode so as to become a control mode suitable for the driving place and time zone of the vehicle. More specifically, the noise priority mode can be automatically selected in driving places such as urban areas where reduction of exhaust noise is desired, and in time periods such as late at night when reduction of exhaust noise is desired. Furthermore, according to the first embodiment, by using the noise meter 36, when the exhaust noise actually emitted from the exhaust port 34 is large, the noise priority mode can be automatically selected.

Next, another setting example of the VN opening degree α will be described. 9 is a graph for explaining another setting example of the VN opening degree α used in the noise priority mode of the first embodiment. The example shown in FIG. 9 differs from the example shown in FIG. 2 in the setting of the VN opening degree α in the high air volume region R1. Specifically, in the example (dotted line) shown in FIG. 2 , in the high air volume region R1 , the VN 22 maintains the fully closed opening degree against an increase in the required air volume Ga. On the other hand, in the example shown in FIG. 9 (one-dot chain line), the VN opening degree α in the high air volume region R1 is strictly set such that the full-close opening degree is achieved at the maximum value Gamax. , decreases with a slight slope relative to the increase in the required air volume Ga. However, the change in the VN opening degree α on such a slight slope is a change in the level that "the VN 22 substantially maintains the fully closed opening degree in response to an increase in the required air amount Ga". As in the example of the one-dot chain line shown in FIG. 9, the VN opening degree α in the high air volume region R1 used in the noise priority mode may be set to substantially increase with respect to the increase in the required air volume Ga. maintained at a fully closed opening.

Next, a second embodiment will be described. The second embodiment differs from the first embodiment in that "the VN opening degree α and the throttle opening degree α with respect to the required air amount Ga when the noise priority mode is executed using the VN opening degree α and the throttle valve opening degree θ The setting of degree θ".

10 is a graph for explaining a fuel economy priority mode and a noise priority mode in the second embodiment. The setting of the VN opening degree α and the throttle valve opening degree θ in the fuel economy priority mode is the same as that of the first embodiment.

As shown in FIG. 10 , in the noise priority mode, in the second embodiment as in the first embodiment, VN 22 starts to close at a specific required air amount Ga1 in response to an increase in the required air amount Ga.

For the high flow side with respect to a specific required air amount Ga1, in the first embodiment, the VN opening α gradually (monotonically) decreases to the fully closed opening with respect to an increase in the required air amount Ga. In contrast, in the second embodiment, after the VN opening degree α gradually decreases with the increase of the required air amount Ga, the high flow rate after the required air amount value Ga2 (< Gamax) before reaching the fully closed opening degree On the side, the VN opening degree α gradually decreases toward the fully closed opening degree with respect to an increase in the required air volume Ga with a gentler slope than that on the low flow side. The throttle opening θ is adjusted so as to satisfy the required air amount Ga under the setting of the VN opening α changed in this way from the first embodiment.

In FIG. 10 , the same high air volume region R1 as shown in FIG. 2 is used as an example of the "high air volume region" of the present invention. According to the noise priority mode of the second embodiment, in the high air volume region R1 , the throttle valve opening θ is increased while decreasing the VN opening α in response to an increase in the required air volume Ga. More specifically, in the example shown in FIG. 10 , in the high air volume region R1 , the throttle opening θ is increased while decreasing the VN opening α in response to an increase in the required air volume Ga until the required air volume Ga is increased. Ga reaches the maximum value Gamax.

According to the above-mentioned setting of the noise priority mode shown in FIG. α becomes the open side, and the throttle opening θ increases accordingly. As a result, although the reduction amount of exhaust noise is reduced compared with the setting of the first embodiment, fuel economy is improved due to the reduction of pump loss.

Here, in the noise priority mode, the allowable fuel economy deterioration amount when the VN opening degree α is set to the closed side compared with the fuel economy priority mode may differ depending on the engine operating conditions. The setting of the noise priority mode shown in FIG. 10 is suitable for use under engine operating conditions in which the allowable deterioration in fuel efficiency is small in a high air mass region such as the high air mass region R1. In addition, regarding the noise priority mode, for example, it is also possible to use the setting shown in FIG. The settings shown in Fig. 2 are used under engine operating conditions where the amount of performance deterioration is relatively large.

In addition, according to the setting of the VN opening degree α in the noise priority mode according to the second embodiment described above, when compared with the fuel economy priority mode, similarly to the first embodiment, in the high air volume region R1 The VN opening degree α is controlled toward the closing side. Therefore, also according to the noise priority mode of the second embodiment, it is possible to realize the requested engine torque while reducing the exhaust noise.

Next, a third embodiment will be described. FIG. 11 is a schematic diagram showing an example of a system configuration of an internal combustion engine 60 according to the third embodiment. This internal combustion engine 60 differs from the internal combustion engine 10 shown in FIG. 1 in that a variable valve mechanism 62 is additionally provided. The variable valve mechanism 62 is configured to be able to change the opening characteristics of the intake valve 64 (for example, the lift amount, opening timing, and closing timing of the intake valve 64 ) of each cylinder.

In the intake air amount control (fuel economy priority mode and noise priority mode) in the third embodiment, the intake air amount is controlled so as to satisfy the required air amount Ga at the VN opening degree α corresponding to the required air amount Ga , using the variable valve train 62 together with the throttle valve 28 . In addition, in order to perform such intake air amount control, a variable valve mechanism capable of changing the opening characteristic of the exhaust valve 66 may be used together with the variable valve mechanism 62 .

12 is a graph for explaining a fuel economy priority mode and a noise priority mode in the third embodiment. The setting of the VN opening degree α and the throttle valve opening degree θ in the fuel economy priority mode is the same as that of the first embodiment.

As shown in FIG. 12 , in the noise priority mode, in the third embodiment as in the first embodiment, VN 22 starts closing at a specific required air amount Ga1 in response to an increase in the required air amount Ga.

On the high flow side with respect to the specific required air volume value Ga1, in the third embodiment as in the first embodiment, the VN opening degree α gradually (monotonically) increases with respect to the increase in the required air volume Ga1. Reduced to fully closed opening. The difference between the two is the "decrease slope of the VN opening degree α with respect to the increase in the required air amount Ga". That is, as shown in FIG. 12 , in the third embodiment, the VN opening degree α decreases toward the fully closed opening degree with a slope greater than that in the first embodiment.

According to the setting of the VN opening degree α in the noise priority mode of the third embodiment described above, compared with the setting of the first embodiment, the air volume region (load region) using the fully closed opening degree of VN22 can be shifted to The low flow side (low load side) expands. Therefore, the setting of the VN opening degree α in the third embodiment is suitable for use in a case where "the engine load region requiring exhaust noise reduction exists on the lower load side".

In addition, instead of setting the VN opening degree α of the third embodiment, for example, by shifting the specific required air volume value Ga1 to the low flow rate side, it is possible to make the above-mentioned slope the same as that of the first embodiment and to expand the use of The air volume area of the fully closed opening of the VN22. However, in this method, compared with the setting shown in FIG. 12 , the air volume region in which VN22 is closed is enlarged toward the low flow rate side with respect to the full opening degree. This leads to deterioration of fuel economy in a small air volume region (low load region) where reduction of pump loss for improving fuel economy is required. In addition, in the small air volume region, the exhaust noise value itself is smaller than that on the high air volume side. Therefore, according to the setting of the VN opening degree α in the third embodiment, it is possible to enhance the exhaust noise reduction effect while also taking these points into consideration.

In addition, in the noise priority mode of the third embodiment, the throttle valve opening θ and the opening characteristic of the intake valve 64 are controlled so that the required air amount Ga is satisfied at the VN opening α set as described above. Specifically, on the low flow rate side of the specific required air volume value Ga1 or less, as an example, only the same control of the throttle opening θ as in the first embodiment is executed.

On the other hand, an air volume region R2 exists in an air volume region on the high flow side of the specific required air volume value Ga1 and on the low flow side of the high air volume region R1 . In this air volume region R2, with respect to the increase in the required air volume Ga, the VN opening α and the throttle valve opening θ are kept constant (or substantially constant) while satisfying the required air volume Ga. A variable valve train 62 controls the opening characteristics of an intake valve 64 . More specifically, in order to increase the intake air amount relative to the increase in the required air amount Ga, for example, at least one of the lift amount, opening timing, and closing timing of the intake valve 64 is controlled.

In addition, according to the setting of the VN opening degree α according to the noise priority mode of the third embodiment described above, when compared with the fuel economy priority mode, similarly to the first embodiment, in the high air volume region R1 The VN opening degree α is controlled toward the closing side. Therefore, also according to the noise priority mode of the third embodiment, it is possible to realize the required engine torque while reducing the exhaust noise.

In addition, as described above with reference to FIG. 9 in connection with the first embodiment, in the setting of the VN opening α in the noise priority mode of the third embodiment (see FIG. 12 ), the VN opening α may be Instead of strictly maintaining the fully-closed opening with respect to an increase in the required air amount Ga, it is controlled so that the fully-closed opening is substantially maintained.

In addition, "the variable valve mechanism 62 is used together with the throttle valve 28 so that the required air amount Ga is satisfied at the VN opening degree α set in the noise priority mode" requires attention to the following points, and is not limited to the third embodiment. The noise priority mode of the present embodiment can also be applied to the noise priority modes of the other first and second embodiments. That is, regarding the noise priority mode shown in FIG. 2 , the throttle opening θ may be adjusted while maintaining the fully closed opening of VN22 in the high air volume region R1 with respect to the increase in the required air volume Ga. "Increase" is set as a condition, and the variable valve mechanism 62 is used together with the throttle valve 28 in order to satisfy the required air amount Ga. In addition, regarding the noise priority mode shown in FIG. 10 , it is also possible to increase the throttle opening θ while decreasing the VN opening α with respect to the increase in the required air quantity Ga in the high air volume region R1. With this setting as a condition, in order to satisfy the required air amount Ga, the variable valve mechanism 62 is used together with the throttle valve 28 .

Next, a fourth embodiment will be described. In the fourth embodiment, a method for reducing noise under engine operating conditions in which the ignition timing can be advanced so as to approach the optimum ignition timing (MBT (Minimum advance for the Best Torque) ignition timing) will be described. The VN opening degree α is corrected so that the closing amount of the VN opening degree α in the priority mode becomes large without deteriorating fuel economy. In the following description, the setting of the VN opening degree α in the noise priority mode shown in FIG. 2 of the first embodiment will be targeted. However, this correction method can be similarly applied to the setting of the VN opening degree α in the noise priority mode shown in FIGS. 10 and 12 of the second embodiment and the third embodiment.

Specifically, when the ECU 40 using the method of correcting the VN opening degree α of the fourth embodiment selects the noise priority mode under the engine operating condition that selects the basic ignition timing on the retard side with respect to the MBT ignition timing, such that The ignition device 46 is controlled so that the ignition timing SA is advanced from the basic ignition timing SAb to approach the MBT ignition timing, and the "fuel economy improvement amount (ΔBSFC described later) associated with this advancement of the ignition timing SA is offset." ” to correct the VN opening α set in the noise priority mode to the closed side. In addition, in the example shown in FIG. 2 , the VN opening α to be corrected by this correction method gradually decreases from the fully open opening toward the fully closed opening as the required air amount Ga increases. The VN opening degree α of the air volume area.

13 is a flowchart showing calculation processing of the VN opening degree α in the noise priority mode using the method of correcting the VN opening degree α according to the fourth embodiment. The processing of this flowchart is executed in conjunction with the processing of step S106 in the flowchart shown in FIG. 6 described above.

In FIG. 13 , the ECU 40 first obtains the operating state parameters of the internal combustion engine 10 in step S200 . The operating state parameters referred to here are parameters that affect the ignition timing (for example, engine water temperature Tw and intake air temperature Tb). The engine water temperature Tw and the intake air temperature Tb are detected using, for example, an engine water temperature sensor and an intake air temperature sensor. Then, the process proceeds to step S202.

In step S202 , the ECU 40 determines whether or not the engine operating condition is such that the ignition timing SA can be advanced so as to approach the MBT ignition timing.

FIG. 14 is a graph showing the relationship between BSFC and ignition timing SA. As shown in FIG. 14, BSFC (fuel economy) becomes optimum at MBT ignition timing. FIG. 14 corresponds to an example of the engine operating conditions for which the determination result of step S202 is YES. That is, the basic ignition timing (typically a value corresponding to the engine load and the engine speed) SAb under the engine operating conditions corresponding to FIG. 14 is on the retard side of the MBT ignition timing. Therefore, there is room for correcting the ignition timing SA with respect to the basic ignition timing SAb so as to approach the MBT ignition timing, and as a result, BSFC can be improved.

On the other hand, when the ignition timing SA is advanced, knocking is likely to occur. Therefore, in this step S202 , in addition to the determination of whether there is room for advancing the ignition timing, it is also determined whether the engine operating condition is an engine operating condition that can be advanced without deteriorating the occurrence of knocking. Specifically, for example, when the engine water temperature Tw is lower than a predetermined value because the engine is warming up, the latter determination result is YES. In addition, for example, when the capacity of the intercooler 26 is sufficient because the vehicle is running at high speed, the intake air temperature Tb can be lowered from the current detected value, so the latter determination result is also YES.

When the results of the two determinations in step S202 are YES, the ECU 40 finally determines that the ignition advance is possible, and the process proceeds to step S204. On the other hand, when one or both of the results of the above two determinations are negative, the ECU 40 finally determines that the ignition advance cannot be performed, and ends the processing of the flowchart shown in FIG. 13 . In this case, as already described with reference to step S106 , the VN opening degree α is calculated from the relationship (map) shown in FIG. 8A corresponding to the setting of the VN opening degree α shown in FIG. 2 .

In step S204, the ECU 40 calculates an advance amount ΔSA of the ignition timing SA. The advance amount ΔSA is calculated based on, for example, the difference ΔTw between the basic value of the engine water temperature Tw (the value associated with the basic ignition timing SAb) and the current value (the value obtained in step S200 ). Specifically, for example, the advance amount ΔSA is calculated so that the larger the difference ΔTw is, the larger the advance amount ΔSA is. Then, the process proceeds to step S206.

In step S206 , the ECU 40 calculates a fuel economy improvement amount ΔBSFC corresponding to the calculated advance amount ΔSA. The fuel economy improvement amount ΔBSFC can be calculated using the relationship between BSFC and ignition timing SA as shown in FIG. 14 . More specifically, this relationship changes according to each of the required air amount Ga (engine load) and the engine speed. Therefore, a map defining the relationship between the ignition timing SA, the required air amount Ga, the engine speed, and the BSFC is stored in the memory 40b. The ECU 40 calculates the fuel economy improvement amount ΔBSFC according to the current advance amount ΔSA, the required air amount Ga, and the engine speed based on such a map. Then, the process proceeds to step S208.

In step S208 , the ECU 40 calculates a VN opening αc corrected from the basic VN opening αb in the noise priority mode to the closed side by an amount that cancels out the calculated fuel economy improvement amount ΔBSFC. The basic VN opening degree αb referred to here corresponds to the VN opening degree α calculated from the relationship (map) shown in FIG. 8A corresponding to the setting of the VN opening degree α shown in FIG. 2 .

FIG. 15 is a graph showing the relationship between the BSFC used in step S208 and the VN opening degree α. As already explained, when the VN opening degree α moves to the closed side, basically the BSFC (fuel economy) deteriorates due to an increase in the pump loss. Therefore, by utilizing the relationship shown in FIG. 15 , it is possible to determine the VN opening degree αc that degrades the fuel economy by the fuel economy improvement amount ΔBSFC with respect to the value of BSFC at the basic VN opening degree αb. More specifically, this relationship changes according to each of the required air amount Ga (engine load) and the engine speed. Therefore, a map for specifying the relationship between the BSFC and the VN opening degree α is stored in the memory 40b as a map that differs depending on the required air amount Ga and the engine speed. Using such a map, the ECU 40 calculates the VN opening degree αc that is on the closing side with respect to the basic VN opening degree αb by "an amount that cancels out the fuel economy improvement amount ΔBSFC".

Further, the ECU 40 controls the ignition device 46 so that the basic ignition timing SAb is advanced from the basic ignition timing SAb by the advance amount ΔSA calculated by the process of the flowchart shown in FIG. The VN actuator 24 is controlled in such a manner that the VN opening degree αc calculated by processing (that is, after correction) is obtained.

According to the method of correcting the VN opening degree α of the fourth embodiment described above, under the engine operating conditions in which the ignition timing SA can be advanced so as to approach the MBT ignition timing, it is possible to reduce noise without deteriorating fuel economy. The closing amount of the VN opening degree α used in the priority mode (as the difference between the basic VN opening degree αb and the corrected VN opening degree αc) is increased. Therefore, it is possible to increase the effect of reducing exhaust noise by utilizing the noise priority mode without accompanying deterioration in fuel economy.

In addition, under the low engine water temperature condition, which is one of the above-mentioned engine operating conditions, engine noise (mechanical noise) becomes louder due to an increase in engine friction, and in addition, due to an increase in the required air amount Ga caused by an increase in engine friction, , the combustion noise becomes louder. In this regard, by using the corrected VN opening degree αc based on the correction method of the fourth embodiment to reduce exhaust noise under such a low engine water temperature condition, the noise level of the entire vehicle can be reduced.

Claims (10)

1. A control device of an internal combustion engine is applied to the internal combustion engine,

the internal combustion engine includes a variable-section turbocharger having a turbine with a variable nozzle and an actuator configured to control an opening degree of the variable nozzle, and a throttle valve disposed in an intake passage,

the control device is characterized by comprising an electronic control unit,

the electronic control unit is configured to,

a first control mode, which is one of the control modes of the intake air amount, is included, and,

when the air quantity region on the high flow rate side including the maximum value of the required air quantity of the internal combustion engine is referred to as a high air quantity region,

in the first control mode of operation in the first mode of operation,

on the maximum value side in the high air amount region, the actuator and the throttle valve are controlled so that the throttle valve opening is increased while the variable nozzle is maintained at a fully closed opening or a substantially fully closed opening with respect to an increase in the required air amount,

alternatively, the actuator and the throttle valve may be controlled so that the throttle valve opening is increased while the variable nozzle opening is decreased with respect to the increase in the required air amount at the maximum value side in the high air amount region.

2. The control apparatus of an internal combustion engine according to claim 1, wherein,

the electronic control unit includes a second control mode as another control mode among the control modes, and,

the electronic control unit is configured to,

in the second control mode of operation in the first control mode,

on the maximum value side in the high air amount region, the actuator and the throttle valve are controlled so that the variable nozzle opening is reduced while the throttle valve is maintained at a full opening or a substantially full opening with respect to an increase in the required air amount,

in the first control mode, fuel economy is deteriorated and exhaust noise is reduced as compared with the second control mode.

3. A control device of an internal combustion engine is applied to the internal combustion engine,

the internal combustion engine includes a variable-section turbocharger having a turbine with a variable nozzle and an actuator configured to control the opening degree of the variable nozzle, a throttle valve disposed in an intake passage, and a variable valve mechanism configured to be able to change the opening characteristic of an intake valve,

the control device is characterized by comprising an electronic control unit,

The electronic control unit is configured to,

a first control mode, which is one of the control modes of the intake air amount, is included, and,

when the air quantity region on the high flow rate side including the maximum value of the required air quantity of the internal combustion engine is referred to as a high air quantity region,

in the first control mode of operation in the first mode of operation,

on the maximum value side in the high air amount region, the throttle valve and the variable valve mechanism are controlled so as to satisfy the required air amount while controlling the actuator so as to maintain the variable nozzle at the full-close opening or substantially the full-close opening, or so as to reduce the variable nozzle opening, with respect to the increase in the required air amount.

4. The control apparatus of an internal combustion engine according to claim 3, wherein,

the electronic control unit includes a second control mode as another control mode among the control modes, and,

the electronic control unit is configured to,

in the second control mode of operation in the first control mode,

on the maximum value side in the high air amount region, the actuator and the throttle valve are controlled so that the variable nozzle opening is reduced while the throttle valve is maintained at a full opening or a substantially full opening with respect to an increase in the required air amount,

In the first control mode, fuel economy is deteriorated and exhaust noise is reduced as compared with the second control mode.

5. The control device for an internal combustion engine according to claim 2 or 4, characterized in that,

the electronic control unit is configured to control the actuator such that the variable nozzle is started and closed from the full-open degree in the first control mode with respect to an increase in the required air amount at a specific required air amount value smaller than that during execution of the second control mode.

6. The control apparatus of an internal combustion engine according to claim 5, wherein,

the electronic control unit is configured to control the actuator in such a manner that the variable nozzle opening is gradually reduced toward the full-close opening and then the variable nozzle is maintained at the full-close opening or substantially the full-close opening with respect to an increase in the required air amount in the air amount region on the high flow rate side higher than the specific required air amount value in the first control mode.

7. The control device for an internal combustion engine according to any one of claims 1 to 4, characterized in that,

The internal combustion engine comprises an ignition device,

the electronic control unit is configured to control the ignition device so as to advance an ignition timing from a base ignition timing in order to approach an optimum ignition timing when the first control mode is selected under an engine operation condition in which the base ignition timing on a retard side with respect to the optimum ignition timing is selected, and,

the electronic control unit is configured to correct the variable nozzle opening degree set in the first control mode to a closing side by an amount that cancels the fuel economy improvement amount accompanying the advancement of the ignition timing.

8. The control device for an internal combustion engine according to any one of claims 1 to 4, characterized in that,

the vehicle mounted with the internal combustion engine includes an input device configured to receive a noise priority request from a driver to reduce exhaust noise over fuel economy,

the electronic control unit is configured to select the first control mode when the input device receives the noise priority request.

9. The control device for an internal combustion engine according to any one of claims 1 to 4, characterized in that,

The electronic control unit is configured to select the first control mode when a vehicle on which the internal combustion engine is mounted is traveling in at least one of a place and a time period in which exhaust noise reduction is to be prioritized over fuel economy.

10. The control device for an internal combustion engine according to any one of claims 1 to 4, characterized in that,

the vehicle on which the internal combustion engine is mounted includes a noise meter configured to measure exhaust noise emitted from an exhaust port, and,

the electronic control unit is configured to select the first control mode when a value of the exhaust noise measured by the noise meter is higher than a threshold value.